title: Activation of Leishmania spp. leishporin: evidence that dissociation of an inhibitor not only improves its lipid-binding efficiency but also endows it with the ability to form pores.
abstract: We have previously shown that various species of Leishmania produce a lytic activity, which, in Leishmania amazonensis, is mediated by a pore-forming cytolysin, called leishporin. It is toxic for macrophages in vitro and optimally active at pH 5.0 to 5.5 and at 37 °C, suggesting that it might be active inside phagolysosomes. Leishporin from both L. amazonensis (a-leishporin) and Leishmania guyanensis (g-leishporin) can be activated by proteases, suggesting either a limited proteolysis of an inactive precursor or a proteolytic degradation of a non-covalently linked inhibitor. Here, we show that both a- and g-leishporin are also activated in dissociating conditions, indicating the second hypothesis as the correct one. In fact, we further demonstrated that inactive leishporin is non-covalently associated with an inhibitor, possibly more than one oligopeptide that, when removed, renders leishporin hemolytically active. This activation was shown to be the result of both the improvement of leishporin's ability to bind to phospholipids and the emergence of its pore-forming ability. In vitro results demonstrate that leishporin can be released by the parasites, as they evolve in axenic cultures, in an inactive form that can be activated. These results are compatible with our hypothesis that leishporin can be activated in the protease-rich, low pH, and dissociating environment of parasitophorous vacuoles, leading to disruption of both vacuoles and plasma membranes with the release of amastigotes.
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil.
authors.forename: Flávia Regina
authors.initials: FR
authors.lastname: Almeida-Campos
authors.forename: Thiago
authors.initials: T
authors.lastname: Castro-Gomes
authors.forename: Alice
authors.initials: A
authors.lastname: Machado-Silva
authors.forename: Jamil Silvano
authors.initials: JS
authors.lastname: de Oliveira
authors.forename: Marcelo Matos
authors.initials: MM
authors.lastname: Santoro
authors.forename: Frédéric
authors.initials: F
authors.lastname: Frézard
authors.forename: Maria Fátima
authors.initials: MF
authors.lastname: Horta
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003603:Cytotoxins / Q000378:metabolism; D004789:Enzyme Activation; D004912:Erythrocytes / Q000469:parasitology* / Q000502:physiology; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007891:Leishmania / Q000378:metabolism*; D007896:Leishmaniasis / Q000469:parasitology*; D008563:Membrane Lipids / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism*; D013696:Temperature
chemical_list: D003603:Cytotoxins; D008563:Membrane Lipids; D015800:Protozoan Proteins; C412371:leishporin protein, Leishmania; D010447:Peptide Hydrolases